1. Field of the Invention
The present invention relates to devices for the spine and, more particularly, to spinal implants for providing interspinous and/or inter-laminar space between adjacent vertebrae.
2. Background Information
As we age various changes can occur in the body. For instance, the ligaments of the spine can thicken and calcify (i.e. harden from deposits of calcium), bone and joints may enlarge, bone spurs called osteophytes may form, spinal discs may collapse and bulge (i.e. herniate) or one vertebra may slip over another (spondylolisthesis). Any one or these conditions and/or others can cause what is known as lumbar spinal stenosis. Lumbar spinal stenosis is a narrowing of the bony spinal canal. While some people are born with this condition, most often spinal stenosis is the result of one of the above-identified degenerative conditions that develop in mainly the middle-aged and elderly population.
In this regard, spinal stenosis may be considered as the gradual result of aging and “wear and tear” on the spine from everyday activities. Such degenerative or age-related changes in our bodies can lead to compression of nerves (i.e. pressure on the nerves that can cause pain and/or damage). Symptoms of lumbar spinal stenosis include leg pain (“pins and needles”) that can limit standing, walking, self-supporting daily activities, work social and recreational pursuits. Lack of activity because of lumbar spinal stenosis may lead to obesity, depression and general physical deterioration. Surgical procedures may be used in order to alleviate the problems associated with spinal stenosis. This may include the use of an implant designed to hold or stabilize adjacent vertebrae or vertebral parts of the spine.
Other spinal conditions, diseases and/or accidents, however, can also cause problems that may require spinal surgery and the need to hold or stabilize adjacent vertebrae or vertebral parts in a spatial orientation relative to one another and/or with regard to other vertebral parts. In these cases, the surgeon may again use a device to hold or stabilize adjacent vertebrae or vertebral parts. The implants used for these purposes are typically not affixed to the vertebrae by bone screws or the like but are held to the vertebrae by the bony portions, structures or protrusions of the vertebrae.
Of these types of spinal devices some allow for movement between the adjacent vertebrae to which it is connected and some do not. The static spinal device provides a fixed or static spatial orientation of the adjacent vertebrae to which it is affixed. The static spinal devices permanently limit movement between the adjacent vertebrae to which it is affixed. The non-static spinal devices provide limited movement between the adjacent vertebrae in addition to maintaining a spatial orientation of the adjacent vertebrae. These non-static spinal devices, however, are assemblies formed of two or more components with a variety of ways to achieve motion between the various components.
In view of the above, it is apparent that there is a need for improved interspinous or inter-laminar spinal devices, both flexible and static one-piece designs.